The present invention relates to a hydraulic circuit for a backhoe, and more particularly to a hydraulic circuit comprising a first parallel type multiple valve including control valves connected to a first pump in parallel to one another for driving part of a plurality of working implements, a second parallel type multiple valve including further control valves connected to a second pump in parallel to one another for driving remaining working implements, and a confluence mechanism for combining a hydraulic pressure from the first pump and a hydraulic pressure from the second pump for delivery to an attachment control valve,
FIG. 3 shows such a hydraulic circuit known in the art. This circuit comprises a first multiple valve A and a second multiple valve B formed separately, and a confluence mechanism C. The confluence mechanism C includes an attachment control valve V7 connected in parallel to the first multiple valve A and having a third center bypass line R3 connected to a rear end of a first center bypass line R1, and a confluence block 7 mounted in the first multiple valve A for connecting a rear end of a second center bypass line R2 of the second multiple valve B to a rear end of a parallel circuit 10 of the first multiple valve A.
When assembling the control valves into the backhoe, however, this construction requires a troublesome operation of assembling the first and second multiple valves A and B separately. Furthermore, the first multiple valve A must have a considerable length since oil cannot be supplied from the second multiple valve B to the attachment control valve V7 unless the confluence block 7 is mounted in the first multiple valve A. As a result, these valves on the whole require a large accommodating space.